#include<stdio.h>
int f(int n);
int main()
{
	int n, i;
	double sum = 1.;
	scanf("%d", &n);
	for (i = 1; i <= n; i++)
	{
		sum = sum + 1. / f(i);
	}
	printf("%.10f", sum);
	return 0;
}
int f(int n)
{
	if (n == 1)
		return 1;
	else
		return f(n - 1) * n;
}